This invention is concerned with the detection of humidity of a hot gas stream. Various machines, such as the Yankee Dryer exist involving gas streams flowing at extremely high temperatures, such as 1000.degree. F. In such high temperature/high humidity environments it would be desirable to determine the humidity of the gas stream for various control purposes. Commonly assigned patent application Ser. No. 847,670, filed Apr. 3, 1986, the details of which are incorporated herein by reference thereto, discloses an approach for determining the humidity. The present invention is directed to variations of the teachings of that application.